The main objective of our proposed research is to explore any structural difference between antigen receptor immunoglobulins present in human B lymphocyte and their counterparts in secretion, in order to obtain the precise knowledge of the mode of attachment of these antigen receptor molecules to the lymphocyte membrane. The structural studies will employ peripheral blood lymphocytes obtained from patients with chronic lymphatic leukemia as well as human lymphoblastoid cells transformed by virus and cultured. The methods to be utilized include analysis of CNBr-cleavage, tryptic digestion as well as reduction-alkylation products. The knowledge obtained will be compiled to obtain the necessary information to explain how antigen-receptor molecules are embedded to the lymphocyte membrane.